| /* |
| * RTP H.263 Depacketizer, RFC 2190 |
| * Copyright (c) 2012 Martin Storsjo |
| * Based on the GStreamer H.263 Depayloder: |
| * Copyright 2005 Wim Taymans |
| * Copyright 2007 Edward Hervey |
| * Copyright 2007 Nokia Corporation |
| * Copyright 2007 Collabora Ltd, Philippe Kalaf |
| * Copyright 2010 Mark Nauwelaerts |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include "avformat.h" |
| #include "avio_internal.h" |
| #include "rtpdec_formats.h" |
| #include "libavutil/attributes.h" |
| #include "libavutil/intreadwrite.h" |
| #include "libavcodec/get_bits.h" |
| |
| struct PayloadContext { |
| AVIOContext *buf; |
| uint8_t endbyte; |
| int endbyte_bits; |
| uint32_t timestamp; |
| int newformat; |
| }; |
| |
| static void h263_close_context(PayloadContext *data) |
| { |
| ffio_free_dyn_buf(&data->buf); |
| } |
| |
| static int h263_handle_packet(AVFormatContext *ctx, PayloadContext *data, |
| AVStream *st, AVPacket *pkt, uint32_t *timestamp, |
| const uint8_t *buf, int len, uint16_t seq, |
| int flags) |
| { |
| /* Corresponding to header fields in the RFC */ |
| int f, p, i, sbit, ebit, src, r; |
| int header_size, ret; |
| |
| if (data->newformat) |
| return ff_h263_handle_packet(ctx, data, st, pkt, timestamp, buf, len, |
| seq, flags); |
| |
| if (data->buf && data->timestamp != *timestamp) { |
| /* Dropping old buffered, unfinished data */ |
| ffio_free_dyn_buf(&data->buf); |
| data->endbyte_bits = 0; |
| } |
| |
| if (len < 4) { |
| av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet: %d\n", len); |
| return AVERROR_INVALIDDATA; |
| } |
| |
| f = buf[0] & 0x80; |
| p = buf[0] & 0x40; |
| if (!f) { |
| /* Mode A */ |
| header_size = 4; |
| i = buf[1] & 0x10; |
| r = ((buf[1] & 0x01) << 3) | ((buf[2] & 0xe0) >> 5); |
| } else if (!p) { |
| /* Mode B */ |
| header_size = 8; |
| if (len < header_size) { |
| av_log(ctx, AV_LOG_ERROR, |
| "Too short H.263 RTP packet: %d bytes, %d header bytes\n", |
| len, header_size); |
| return AVERROR_INVALIDDATA; |
| } |
| r = buf[3] & 0x03; |
| i = buf[4] & 0x80; |
| } else { |
| /* Mode C */ |
| header_size = 12; |
| if (len < header_size) { |
| av_log(ctx, AV_LOG_ERROR, |
| "Too short H.263 RTP packet: %d bytes, %d header bytes\n", |
| len, header_size); |
| return AVERROR_INVALIDDATA; |
| } |
| r = buf[3] & 0x03; |
| i = buf[4] & 0x80; |
| } |
| sbit = (buf[0] >> 3) & 0x7; |
| ebit = buf[0] & 0x7; |
| src = (buf[1] & 0xe0) >> 5; |
| if (!(buf[0] & 0xf8)) { /* Reserved bits in RFC 2429/4629 are zero */ |
| if ((src == 0 || src >= 6) && r) { |
| /* Invalid src for this format, and bits that should be zero |
| * according to RFC 2190 aren't zero. */ |
| av_log(ctx, AV_LOG_WARNING, |
| "Interpreting H263 RTP data as RFC 2429/4629 even though " |
| "signalled with a static payload type.\n"); |
| data->newformat = 1; |
| return ff_h263_handle_packet(ctx, data, st, pkt, timestamp, buf, |
| len, seq, flags); |
| } |
| } |
| |
| buf += header_size; |
| len -= header_size; |
| |
| if (!data->buf) { |
| /* Check the picture start code, only start buffering a new frame |
| * if this is correct */ |
| if (len > 4 && AV_RB32(buf) >> 10 == 0x20) { |
| ret = avio_open_dyn_buf(&data->buf); |
| if (ret < 0) |
| return ret; |
| data->timestamp = *timestamp; |
| } else { |
| /* Frame not started yet, skipping */ |
| return AVERROR(EAGAIN); |
| } |
| } |
| |
| if (data->endbyte_bits || sbit) { |
| if (data->endbyte_bits == sbit) { |
| data->endbyte |= buf[0] & (0xff >> sbit); |
| data->endbyte_bits = 0; |
| buf++; |
| len--; |
| avio_w8(data->buf, data->endbyte); |
| } else { |
| /* Start/end skip bits not matching - missed packets? */ |
| GetBitContext gb; |
| init_get_bits(&gb, buf, len*8 - ebit); |
| skip_bits(&gb, sbit); |
| if (data->endbyte_bits) { |
| data->endbyte |= get_bits(&gb, 8 - data->endbyte_bits); |
| avio_w8(data->buf, data->endbyte); |
| } |
| while (get_bits_left(&gb) >= 8) |
| avio_w8(data->buf, get_bits(&gb, 8)); |
| data->endbyte_bits = get_bits_left(&gb); |
| if (data->endbyte_bits) |
| data->endbyte = get_bits(&gb, data->endbyte_bits) << |
| (8 - data->endbyte_bits); |
| ebit = 0; |
| len = 0; |
| } |
| } |
| if (ebit) { |
| if (len > 0) |
| avio_write(data->buf, buf, len - 1); |
| data->endbyte_bits = 8 - ebit; |
| data->endbyte = buf[len - 1] & (0xff << ebit); |
| } else { |
| avio_write(data->buf, buf, len); |
| } |
| |
| if (!(flags & RTP_FLAG_MARKER)) |
| return AVERROR(EAGAIN); |
| |
| if (data->endbyte_bits) |
| avio_w8(data->buf, data->endbyte); |
| data->endbyte_bits = 0; |
| |
| ret = ff_rtp_finalize_packet(pkt, &data->buf, st->index); |
| if (ret < 0) |
| return ret; |
| if (!i) |
| pkt->flags |= AV_PKT_FLAG_KEY; |
| |
| return 0; |
| } |
| |
| RTPDynamicProtocolHandler ff_h263_rfc2190_dynamic_handler = { |
| .codec_type = AVMEDIA_TYPE_VIDEO, |
| .codec_id = AV_CODEC_ID_H263, |
| .need_parsing = AVSTREAM_PARSE_FULL, |
| .parse_packet = h263_handle_packet, |
| .priv_data_size = sizeof(PayloadContext), |
| .close = h263_close_context, |
| .static_payload_id = 34, |
| }; |
